Sam T. Mugford, Thomas Louveau, R. Melton
Mar 1, 2013
Citations
6
Influential Citations
106
Citations
Quality indicators
Journal
Plant Cell
Abstract
This study reports on an anthranilate N-methyltransferase, MT1, required for synthesis of antimicrobial triterpenoid defense compounds (avenacins) in oat and, through the characterization of MT1 and the products of other genes within the avenacin metabolic gene cluster, presents a model of the subcellular organization of triterpenoid biosynthesis. Operon-like gene clusters are an emerging phenomenon in the field of plant natural products. The genes encoding some of the best-characterized plant secondary metabolite biosynthetic pathways are scattered across plant genomes. However, an increasing number of gene clusters encoding the synthesis of diverse natural products have recently been reported in plant genomes. These clusters have arisen through the neo-functionalization and relocation of existing genes within the genome, and not by horizontal gene transfer from microbes. The reasons for clustering are not yet clear, although this form of gene organization is likely to facilitate co-inheritance and co-regulation. Oats (Avena spp) synthesize antimicrobial triterpenoids (avenacins) that provide protection against disease. The synthesis of these compounds is encoded by a gene cluster. Here we show that a module of three adjacent genes within the wider biosynthetic gene cluster is required for avenacin acylation. Through the characterization of these genes and their encoded proteins we present a model of the subcellular organization of triterpenoid biosynthesis.